playbin2 and gstreamer-vaapi

playbin2 and gstreamer-vaapi

Hello,
I have a question about gstreamer-vaapi plug-in.

I added "video/x-vaapi-surface" to DEFAULT_RAW_CAPS in gst-plugins-base package.
And I did the following command and it played.
> gst-launch -v filesrc location=/home/me/test.mpeg ! qtdemux ! decodebin2 ! vaapisink

Next, I tried to do the following command.
> gst-launch playbin2 uri=file:/home/me/test.mpeg

But the movie does not play. (The movie format is mpeg-4.)
By the log of Gstreamer, I confirmed that vaapidecode element was loaded. But vaapisink element was not loaded. I want to know why vaapisink was not loaded.
Please teach me.